[osg-users] Function collaboration multi-threaded databasepager

Lambert Verhagen l.verhagen at marin.nl
Mon Sep 3 05:37:31 PDT 2007


Hi Robert,

Thank you for the quick response.

I don't understand it completely. Must be me not questioning right ;-).

What I want to develop is an application that:
1) reads data that may contain from scene data like new nodes that are
moving (AddNode). This data feed may also result in a removeNode (since
another application may have decided to remove it from the scene. The
scene graph is constantly, dynamically changed.
2) has an Update-Cull-draw pipe, that runs synchronous (real-time) and
in the update step reads data from the graph that is dynamically changed
by step 1.

For this I thought I need an a-synchronous database thread that read
data from the network (other application) and fills the database at
low(er) frequency. And I also need a fast synchronous thread that reads
data from the database (this must be quick, so probably I need
references to the database scene graph nodes).

The applications like Viewer en CompositeViewer perform updates to the
scene graph via NodeCallbacks that are called from the same thread as
the update-cull-draw thread is running. Isn't it????

Hope you can me further.

Regards,
Lambert

On Mon, 2007-09-03 at 09:52 +0100, Robert Osfield wrote:
> Hi Lambert,
> 
> The OSG has the osgDB::DatabasePager which sole purpose is to do
> multi-threaded paging of databases.  The osgViewer::Viewer and
> CompositeViewer both support it out of the box, as did
> osgProducer::Viewer before it.  There is nothing you need to do in
> your app other than load a paged database. Paged dabases in the OSG
> are ones that contain osg::PagedLOD node or loaded via the TXP plugin.
> 
> Robert.
> 
> On 9/3/07, Lambert Verhagen <l.verhagen at marin.nl> wrote:
> > Hi,
> >
> > I investigating the usage of openscenegraph for one of our application.
> > I want to run this application using 1 thread for the update-cull-draw
> > pipe. And another thread, that runs on the background with lower
> > priority, that receives data from some external network and updates the
> > graph.
> >
> > I can not exactly find a sample application using this multi threaded
> > approach. But the function interface of databasepager suggests that this
> > is supported. Can someone give me a clue?
> > I also want to know the function collaboration between the view,
> > updateVisitor, node and dataBasePager classes.
> >
> > Hope you can help me?
> > Thanks in advance.
> > Regards,
> > Lambert
> >
> >
> > Interested in MARIN's R&D 2007? Subscribe to the MARIN R&D seminar for the Dutch Industry on September 12.
> >
> >
> > This e-mail and its content are subject to the disclaimer and General Conditions at www.marin.nl
> > 


Interested in MARIN's R&D 2007? Subscribe to the MARIN R&D seminar for the Dutch Industry on September 12.


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